采用远场地震波资料和有限断层反演方法获得2021年7月29日6时15分（UTC）美国阿拉斯加州以南海域M_W8.2地震的震源破裂过程模型，探讨此次地震发生的动力学背景。破裂过程反演的结果显示这次地震的滑动量分布比较集中，破裂长度约为160km，地震主体破裂发生在20～40km深度范围内，破裂由深部向浅部发展，表明此次地震释放了俯冲带浅部的应变能，破裂持续时间近120s，破裂面上最大滑移量达5m。此外，主震破裂区域中的余震分布较小，大部分余震发生在主震南部，出现这种现象表明震源区的破裂较为彻底并触发了俯冲带浅部位置的地震，本次地震的有限断层反演结果和余震分布均显示破裂向东发展，但未破裂至震中以西的舒马金空区，表明舒马金空区东部的地震危险性仍然存在。

On July 29, 2021, an earthquake with magnitude 8.2 occurred in the southern part of Alaska Peninsula, USA. In this study, the rupture process of this earthquake is inverted with far-field seismic waveform data for better understanding of the dynamic triggering. the results show that the slip distribution concentrated in adjacent area of the nuclear point, with 160km in length and 20km in depth. the slip model shows a rupture from deep to shallow indicating the stress energy in the shallow subduction zone released in this quake. the rupture process lasts for 120s, the maximum slip achieved 5m. In addition, the aftershock distribution lies in the south of mainshock which implies that rupture in the source region was developed well so as to trigger the earthquakes in the seaward of subduction zone. the distribution of aftershocks and slip displacement was limited in NE direction, not in the SW direction to Shumagin seismic gap, which infers the risk of large earthquake in the east of Shumagin area.

P315

中国地震局监测预报司经常性项目“大震应急产品产出系统运维”（12150411007）资助